feat(ModularBot): pluggable bot with 4 guns, phantom meteor movement, radar harness

- Gun harness: virtual bullet tracker, rolling fitness, auto-selector
- Guns: head-on, linear (extrapolation), circular (integrated formula), tsetlin machine (learning)
- Movement: phantom meteor gravity engine (danger histograms, phantom bullets, fire detection)
- Radar: harness + radar_lock adapter
- Color-coded modules: turret/bullet color per gun, body per movement, scan per radar
- Beats Target, SpinBot, Crazy, TrackFire in 10-round battles

ModularBot_garage/tests/test_gun_selection.nim

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+## Unit test for ModularBot gun selection
+import unittest
+import gun_harness/virtual_bullets as vb
+import gun_harness/selector
+import gun_harness/gun_interface
+
+suite "Gun Selection":
+  test "selector picks best gun and power":
+    # Create a simple tracker with mock vbullets
+    var t = initTracker(4)
+
+    # Spawn some bullets on gun 1 (linear) to simulate tracking history
+    let state = WorldState(
+      enemyX: 100, enemyY: 100, enemySpeed: 5.0, enemyHeading: 0.0,
+      selfX: 50, selfY: 50, selfSpeed: 0.0, selfHeading: 0.0,
+      selfRadarHeading: 0.0, selfEnergy: 100.0,
+      arenaWidth: 800, arenaHeight: 600, tick: 1
+    )
+
+    # Gun 1 (linear) predictions
+    var linPreds: array[len(PowerBins), GunPrediction]
+    for i in 0..<len(PowerBins):
+      linPreds[i] = GunPrediction(x: 105.0 + i.float, y: 105.0 + i.float)
+
+    t.spawnBullets(1, linPreds, state)
+
+    # Simulate a hit on one of the linear gun bullets
+    t.tickBullets(state, proc(gunId: GunId, binIdx: int, fe: FeedbackEvent) =
+      if gunId == 1 and binIdx == 0:
+        check fe.hit == false  # Just verify callback works
+    )
+
+    # Select best shot
+    let (gunId, binIdx, power) = selectShot(t)
+
+    echo "[test] Selected gun=" & $gunId & " binIdx=" & $binIdx & " power=" & $power
+    check gunId >= 0 and gunId < 4  # Should be one of 4 guns
+    check binIdx >= 0 and binIdx < len(PowerBins)  # Valid power bin
+